Materials Article
Materials Article contributed by Antonio Morschbacker, Innovation & Technology Center, Braskem S.A., Rio Grande do Sul, Brazil Bio-Ethanol based Polyethylene Natalie, our covergirl grew up in Ghana: „As kids we ate sugarcane just as it came. I‘m truly amazed that sugarcane today can be converted into plastic“ Braskem is a leading Brazilian company manufacturing thermoplastic resins in Latin America. At the company’s Technology and Innovation Center Braskem has developed the first internationally certified polyethylene made from 100% sugarcane based ethanol. The certification was conducted by Beta Analytic Inc., a leading international laboratory, according to the ASTM-D6866 standard. This standard describes how to determine the biobased content as indicated by 14 C isotope content (see bioplastics MAGAZINE 01/2007 p. 36ff). Polyethylene is the resin with the largest manufacturing capacity in the world, but is currently produced using fossil based raw materials such as naphtha or natural gas. The “green polymer“ developed by Braskem – a high-density polyethylene, one of the resins most widely used in flexible packaging – is the result of a research and development project in which already around 5 million US$ have been invested. Part of this amount of money was allocated to implement an ethylene pilot unit using a high yield ethanol dehydration technology. This is the basis for the production of polyethylene at Braskem’s polymerization pilot plants, which are already producing sufficient quantities for commercial development of the product. One of the biggest advantages of this biopolymer production route is that it will be produced in the same polymerization plants as regular polyethylene. It can be transformed into a wide variety of final products, using the same machines that already exist at Braskem’s customers with no need to invest in new industrial equipment. The stable properties of the ethanol-based plastic and its high energy of combustion, like any other polyethylene, permit it to be fully recovered through mechanical or energy recovery recycling at the end of its useful life. All these aspects indicate a very favorable life cycle analysis for the whole system when compared to the traditional fossil oil based resins or with other biobased alternatives. 26 bioplastics MAGAZINE [03/07] Vol. 2
Materials Brazil has many natural competitive advantages for the development and manufacture of products made from renewable raw materials. Its ethanol fuel program was started in 1975 and is totally based on the sugar cane crop. Since then, the alcohol productivity has been growing about 2.5% per year, from 3.3 m 3 /hectare to 6.9 m 3 /hectare. The total amount produced last season was 17.6 million m 3 and the projections show that there will be an average growth of 9% during the next 8 years, when the current capacity will be doubled. One main characteristic of the sugar cane crop is that it is able to fix a large quantity of carbon and its stalks can be harvested at least four times before they need to be replanted. The amount of lignocellulosic carbon in their leaves and fibres (the so called bagasse) is about twice the amount of sucrose carbon. This feature allows the ethanol process to be self-sufficient in biobased energy with a surplus of 20-30%, when burning just the bagasse. Additionally, a part of the leaves that can be recovered will supply an extra source of energy that can be used in the ethylene process and in the polymerization step of an integrated plant. The project, with an annual productive capacity of 200,000 tonnes, is now under technical and economic specification process and the start up of the “green polyethylene“ production on an industrial scale is expected at the end of 2009. For this first unit Braskem is evaluating the production of some grades from its huge ethylene polymers portfolio, including high density, low density, linear low density, very low density and ultra high molecular weight grades. The plant will be located in Brazil in a place to be determined within the next few months. As the process requires 2.3 m 3 of ethanol to make 1 metric ton of the new plastic, the ethanol consumption will be just a small proportion of the total Brazilian production capacity. The company’s production of plastics from ethanol seeks to supply the main international markets that require products with superior performance and quality, in particular for the automotive, food packaging, cosmetics and personal hygiene industries. Braskem has contacted many leading brands in Brazil and around the world about the possibility of integrating the “green“ plastic into their product lines, enabling them to offer a modern product for the modern needs of millions of consumers. José Carlos Grubisich, Braskem´s CEO, said: “Braskem´s leadership in the green polyethylene project confirms our commitment to innovation and sustainable development and points to the extremely positive prospects for the development of plastic products made from renewable raw materials”. Photo: Hannes Grobe (Wikipedia) bioplastics MAGAZINE [03/07] Vol. 2 27
